The long-range goals of our study are to identify cell surface antigens of human squamous-cell carcinoma using monoclonal antibodies. Particular emphasis will be placed on identifying those antigens that are expressed solely or in greatly increased amounts by tumor cells. To achieve these goals, we will make use of our large panel of human squamous carcinoma cell (SCC) lines and our capacity to culture the corresponding normal cell, the epidermal keratinocyte, as in vitro test systems. We will immunize mice with selected SCC cell lines and select monoclonal antibodies that bind specifically to membrane antigens of this cancer type using an extensive panel of representative cell lines as test cells and hemadsorption assays to assess binding. Antibodies that define antigens that appear to be restricted to squamoua cancers will be further tested by immunoperoxidase tests on tissue sections from a range of normal and tumor tissue. We will study selected antigen-antibody systems further by labeling antigen-bearing target cells with metabolic precursor molecules and solubilizing membrsne antigens. Individual antigens will be selectively precipitated with the corresponding monoclonal antibody and studied for molecular size using polyacrylamide gel electrophoresis and autoradiography enhanced for fluorographic techniques. From this study, we hope to identify antibodies that will bind in a specific or enhanced manner to tumor cells and which may find use as diagnostic or even therapeutic reagents. Initial studies suggest that increased expression on cancer cells of the antigen detected by monoclonal antibody A9 is associated with more aggressive growth in vitro and in vivo (in nude mice). Furthermore, this antibody when labeled with radioactive iodine localizes human squamous cancers in nude mice with a tumor to normal tissue ration of 18:1. (AG)